JP4109686B2 - Coke manufacturing method and pig iron manufacturing method - Google Patents

Description

  The present invention relates to a coke production technique using modified raw coal, and a pig iron production technique using the technique.

  As coking coal for producing blast furnace coke, blended coal of high grade strongly caking coal and low grade weak caking coal or non-caking coal is used. It is because the strength of coke obtained is improved by blending high-grade strong caking coal, and further, gas permeability during operation in a blast furnace can be secured. However, high-grade strong caking coal is gradually being depleted, and its raw material costs are rising, and there is a technology for reforming low-grade weakly caking coal and non-caking coal that exist in large quantities. It has been studied (Patent Documents 1 to 4, Non-Patent Document 1).

For example, in Patent Documents 1 and 2, a coal reformed product obtained by mixing pulverized coal and a solvent and heating in an atmosphere of hydrogen under normal pressure or increased pressure is treated to 60 to 25%. It has been disclosed that a caking filler having a volatile content of 90% or more and having a caking strength index of 90% or more is blended with weakly caking coal or non-caking coal. In Patent Documents 3 and 4, brown coal or the like is mixed with a hydrogen donating solvent to form a slurry, which is hydrogenated and liquefied using a catalyst at high temperature and high pressure, and finally refined SRC (solvent refined coal ) Is extracted and used as coking coal.
Japanese Patent Laid-Open No. 51-107301 JP 51-107302 A JP-A-7-53965 JP-A-8-269459 Toru Nishi et al., “About using SRC as a raw material for coke”, Proceedings of the 72nd Coke Special Meeting, p. 46-p. 49 (1982)

  The present invention has been made in view of the above circumstances, and the technology for improving the strength of the obtained coke, and the use of valuable strong caking coal that is a coke production raw material when the coke strength is comparable. It aims at providing the technique which reduces the quantity and increases the usage-amount of weak caking coal or non caking coal.

  The method for producing coke according to the present invention includes a coal having a carbon content (daf) of 85% to 91% and a carbon content (daf) of 60% to less than 85%. There exists a summary in the place which uses raw coal containing 1 mass part or less of coal which does not contain ash substantially with respect to 100 mass parts of coal blend containing containing coal. Coal is generally classified into anthracite, strong caking coal, caking coal, weak caking coal, non-caking coal, lignite, peat, etc., but the definition is not necessarily clear. A part of caking coal may be called adhesive charcoal. Therefore, in the present invention, anthracite coal, strong caking coal, caking coal, weak caking coal, non-caking coal, etc. are classified by carbon content (daf), and anthracite coal is carbon content ( d.af) More than 91% coal, strong caking coal with a carbon content (daf) of 85% or more and 91% or less, caking coal with carbon content (d.a.f.) F.) Is 83% or more and less than 85% coal, weakly caking coal is carbon content (daf) is 80% or more and less than 83% coal, non-caking coal is carbon content (d A.f.) is 78% or more and less than 80% coal, lignite is carbon content (daf) is 70% or more and less than 78% coal, and peat is carbon content (d Af)) less than 70% coal. Here, the carbon content (daf = dry ash free) is the carbon content (% by mass) of organic matter (C, H, O, S, N) excluding moisture and ash content of coal. It can be measured according to JIS M8819. Hereinafter, coal having a carbon content (daf) of 85% or more and 91% or less is simply referred to as “strongly caking coal”, and the carbon content (daf) is 60% or more and 85%. Less than coal may be simply called "non-caking coal etc.".

  In the present invention, the coke strength obtained can be improved by using raw coal in which the coal containing substantially no ash is contained in the above predetermined range. As coal which does not contain the ash content substantially, for example, the carbon content (daf) is extracted from coal having a carbon content (daf) of 60% or more and less than 95% using an organic solvent (excluding hydrogenation). It is preferable to use the soluble component obtained in this way. As said organic solvent, the organic solvent which has a bicyclic aromatic compound as a main component can be mentioned, for example. The present invention includes a method for producing pig iron using coke obtained by the above-described method for producing coke.

  According to the present invention, as a substitute for a part of strongly caking coal that is a raw material for producing coke, a low caking coal or non-caking coal having a carbon content (daf) of 60% or more and less than 95% is used. Coal modified from coal or the like can be used, and can cope with the problem of depletion of strong caking coal and rising raw material costs. Moreover, the obtained coke also has the characteristic that it is excellent in intensity | strength, and can be utilized suitably for manufacture of pig iron in a blast furnace.

  The method for producing coke according to the present invention includes a coal having a carbon content (daf) of 85% to 91% and a carbon content (daf) of 60% to less than 85%. It is characterized by dry-distilling the raw coal containing 1 mass part or less of coal which does not contain ash substantially with respect to 100 mass parts of blended coal containing coal.

  First, coal that does not substantially contain ash used in the present invention (hereinafter sometimes referred to as “ashless coal”) will be described. The ashless coal may be coal that does not substantially contain ash, but may contain a small amount of ash. In such a case, the ash content is preferably 5,000 ppm or less, and more preferably 2,000 ppm or less. In addition, ash is a residual inorganic substance when coal is ashed at 815 ° C. and is made of, for example, silicic acid, alumina, iron oxide, lime, magnesia, alkali metal, or the like.

  In the present invention, the ashless coal is obtained by extracting with an organic solvent from coal having a carbon content (daf) of 60% or more and less than 95% (more preferably 60% or more and less than 85%). It is preferable to use a soluble component. This is because if non-caking coal or the like is used as a starting material, it is not affected by the problem of exhausting strong caking coal. In particular, in the present invention, the coal extracted with the organic solvent is a weakly caking coal, a non-caking coal having a carbon content (daf) of 70% or more and less than 83%, and lignite, or these It is a preferred embodiment to use a mixture of

  Specifically, the ashless coal is obtained by mixing coal with an organic solvent having a carbon content (daf) of 60% or more and less than 95% (more preferably 60% or more and less than 85%). A slurry is prepared, the slurry is heated and aged to extract a soluble component in the organic solvent, and the obtained slurry is separated into a supernatant and a concentrated solution in which solid phase components are concentrated, and the supernatant The ashless coal can be obtained by filtering and removing the organic solvent by evaporation. FIG. 1 is an explanatory view illustrating an apparatus and a process for producing ashless coal. In the tank 1, coal having a carbon content (daf) of 60% or more and less than 95% is mixed with an organic solvent to produce a slurry. The obtained slurry is supplied to an extraction tank 4 where an extraction process is performed by a pump 2. At that time, the slurry is heated to a predetermined temperature by the preheater 3. In the extraction tank 4, after the soluble component is extracted into the organic solvent while stirring the slurry using the stirrer 10, the obtained slurry is supplied to the gravity settling tank 5. In the gravity settling tank 5, gravity settling is performed to settle the solid phase component (arrow 11), and the slurry is separated into a supernatant liquid and a liquid in which the solid phase component is concentrated. The obtained supernatant is supplied to the filter unit 8, and the solid phase component concentrate settled in the gravity sedimentation tank 5 is collected in the solid phase component concentrate receiver 6. The supernatant liquid is filtered by the filter member 7 of the filter unit 8, and the obtained filtrate is recovered in a supernatant liquid receiver 9 that recovers the supernatant liquid. Next, ashless coal can be obtained by evaporating and removing the organic solvent from the collected supernatant. As a method for evaporating and removing the organic solvent from the supernatant, a general drying method such as a spray drying method, a distillation method, or a vacuum drying method can be applied.

  The coal concentration in the slurry is suitably 10 to 35% by mass. The conditions for heating and aging the slurry to extract soluble components in the organic solvent include, for example, the slurry at 300 ° C. Hold at ˜420 ° C. for 5 to 120 minutes to solubilize soluble components in the coal. This is because a temperature lower than 300 ° C. is insufficient to weaken the bonds between the molecules constituting the coal, and the proportion of soluble components that can be extracted from the coal decreases. On the other hand, at a temperature higher than 420 ° C., the pyrolysis reaction of coal becomes active, and recombination of the generated pyrolysis radicals occurs, so that the ratio of soluble components that are extracted also decreases. On the other hand, at a temperature of 300 to 420 ° C., bonds between the molecules constituting the coal are loosened, mild pyrolysis occurs, and the proportion of soluble components extracted from the coal increases. At this time, the mild pyrolysis of coal produces an aromatic-rich component mainly having an average boiling point (Tb50: 50% distillation temperature) of 200 to 300 ° C., which is effectively used as a part of the organic solvent. it can.

  The temperature at which the obtained slurry is separated into a supernatant and a solid phase component concentrate by gravity sedimentation is preferably 300 ° C. or higher and 420 ° C. or lower. This is because if it is lower than 300 ° C., a part of the component dissolved in the liquid phase component may be precipitated, and the yield of ashless coal may be reduced.

  As the organic solvent, a solvent having high coal dissolving power is preferable, and an organic solvent containing a bicyclic aromatic compound approximate to a coal structural unit as a main component is preferable. The organic solvent preferably has a boiling point of 180 ° C to 330 ° C. When the boiling point is lower than 180 ° C., the recovery rate of the organic solvent evaporated and removed from the supernatant may be lowered. On the other hand, when the boiling point exceeds 330 ° C., it is difficult to separate the coal and the organic solvent, and the recovery rate of the organic solvent may be lowered. Specific examples of the bicyclic aromatic compound include aliphatics such as naphthalene (boiling point: 218 ° C); methylnaphthalene (boiling point: 241 to 242 ° C), dimethylnaphthalene (boiling point: 261 to 272 ° C), and trimethylnaphthalene. Examples thereof include naphthalene having a side chain; biphenyl; biphenyl having an aliphatic side chain or an aromatic substituent, or a mixture thereof.

  Examples of coal having a carbon content (daf) of 60% or more and less than 95% used as a starting material for producing ashless coal have the following characteristics, for example. It is preferable to use one. The volatile content of the non-caking coal or the like is preferably 30% or more, more preferably 32% or more, preferably 40% or less, more preferably 36% or less. The average reflectance of the non-caking coal or the like is preferably 0.6 or more, more preferably 0.8 or more, preferably 1.0 or less, more preferably 0.9 or less. The total inert such as non-caking coal is preferably 5% or more, more preferably 15% or more, preferably 35% or less, more preferably 20% or less. The Gieseler maximum fluidity (logMFD) such as the non-coking coal is preferably 3.0 (logddpm) or more, more preferably 3.3 (logddpm) or more, preferably 4.5 (logddpm) or less. It is preferably 3.6 (logddpm) or less. The volatile content can be measured by the method specified in JIS M8812, the average reflectance can be measured by the method specified by JIS M8816, and the Gieseler maximum fluidity (logMFD) can be measured by the Gieseler plastometer method specified by JIS M8801. Further, the total inert (TI) is calculated by the following formula using the ratio of semi-fujinite and the ratio of the microstructure component group (maceral group) in the analysis value of the coal microstructure component (maceral) of JIS M8816. be able to.

  In the formula, MM (mineral matter) means mineral, A means ash (anhydrous base, measured according to JIS M8812), and S means total sulfur content (anhydrous base, measured according to JIS M8813).

  In the coke manufacturing method of this invention, 1 mass part or less, More preferably, 0.7 mass part or less, More preferably, 0.5 mass part or less is contained with respect to 100 mass parts of coal blends mentioned later. It is preferable to use raw coal. Although the minimum of content of ashless coal is not specifically limited, It is preferable that it is 0.2 mass part or more.

  By containing 0.2 parts by mass or more of ashless coal, a substantially significant improvement in the strength of the obtained coke is recognized. In particular, when the content of ashless coal is 0.5 parts by mass, the strength of the obtained coke has the highest value. On the other hand, when the content of ashless coal exceeds 0.5 parts by mass and is 1 part by mass or less, the coke strength is superior to the case where ashless coal is not added. As it increases, the resulting coke strength tends to decrease. And when it exceeds 1 mass part, compared with the case where ashless coal is not added, coke strength will decline on the contrary.

  Next, coal having a carbon content (daf) of 85% or more and 91% or less used in the present invention, and coal having a carbon content (daf) of 60% or more and less than 85%. The blended coal containing and will be described.

  The blended coal contains coal having a carbon content (daf) of 85% to 91% and coal having a carbon content (daf) of 60% to less than 85%. If it does, it will not specifically limit. More preferably, the coal having a carbon content (daf) of 60% or more and less than 85% is a low viscosity having a carbon content (daf) of 78% or more and less than 83%. There may be mentioned carbonized, non-caking coal, or a mixture thereof. As a combination of coal having a carbon content (daf) of 85% to 91% and coal having a carbon content (daf) of 60% to less than 85%, for example, The aspect which consists of a strong caking coal and a weak caking coal, the aspect which consists of a strong caking coal and a non-caking coal, the aspect which consists of a strong caking coal, a weak caking coal, and a non-caking coal, etc. are mentioned. Can do.

  Coal having a carbon content (daf) of 85% or more and 91% or less in blended coal is blended in order to increase the strength of the obtained coke. The amount is preferably 10 parts by mass or more, and more preferably 40 parts by mass or more when the entire blended coal is 100 parts by mass. Even if 1 mass part or less of ashless coal is added to 100 mass parts of blended coal because the caking component is too short when the blending amount of strong caking coal is less than 10 mass parts, the desired Coke strength may not be obtained. On the other hand, although the upper limit of the compounding quantity of strong caking coal is not specifically limited, 100 mass parts is preferable, 90 mass parts is more preferable, and 60 mass parts is further more preferable. It is because the raw material cost at the time of coke manufacture will rise when the compounding quantity of strong caking coal increases too much. On the other hand, coal (non-caking coal, etc.) having a carbon content (daf) of 60% or more and less than 85% is blended so that the total blending amount with the strongly caking coal becomes 100 parts by mass. It is preferable.

  In the present invention, the blended coal obtained by blending strongly caking coal and non-caking coal or the like preferably has the following characteristics. The volatile content of the blended coal is preferably 15% or more, more preferably 26% or more, preferably 35% or less, more preferably 29% or less. The average reflectance of the blended charcoal is preferably 0.65 or more, more preferably 1.00 or more, preferably 1.60 or less, more preferably 1.10 or less. The total inert of the blended coal is preferably 15% or more, more preferably 20% or more, preferably 35% or less, more preferably 23% or less. The Gieseler maximum fluidity (logMFD) of the blended coal is preferably 0.7 (logddpm) or more, more preferably 2.0 (logddpm) or more, preferably 3.5 (logddpm) or less, more preferably 2 .3 (logddpm) or less. The particle size constitution of the blended coal is preferably 3 mm or less, preferably 50% or more, more preferably 75% or more, preferably 90% or less, more preferably 85% or less. The wide numerical range of each characteristic is a suitable range that can be used as a raw material for blast furnace coke, and by making each characteristic within a narrower numerical range, there is a coke that is substantially insignificant in strength. can get.

  The method for producing coke according to the present invention includes a coal having a carbon content (daf) of 85% to 91% and a carbon content (daf) of 60% to less than 85%. It is characterized by dry-distilling the raw coal containing 1 mass part or less of coal which does not contain ash substantially with respect to 100 mass parts of blended coal containing coal.

  The conditions of the carbonization are not particularly limited, and normal carbonization conditions in coke production using a coke oven can be adopted, for example, 950 ° C or higher, more preferably 1000 ° C or higher, 1200 ° C or lower, More preferably, it is preferably carbonized at a temperature of 1050 ° C. or less for 8 hours or longer, more preferably 10 hours or longer, more preferably 24 hours or shorter, more preferably 20 hours or shorter.

  The present invention includes a pig iron manufacturing method characterized by using coke obtained by the coke manufacturing method of the present invention. Since the coke obtained by the production method of the present invention is excellent in strength, it can be suitably used for producing pig iron in a blast furnace. That is, if coke obtained by the production method of the present invention is used, gas permeability at the time of pig iron production in a blast furnace is improved. The pig iron production method in the blast furnace may be a known method. For example, iron ore and coke are alternately layered in the blast furnace, and hot air from the bottom of the blast furnace, and if necessary, pulverized coal. Can be mentioned.

  Hereinafter, the present invention will be described in detail by way of examples. However, the present invention is not limited to the following examples, and all modifications and embodiments without departing from the gist of the present invention are not limited thereto. Included in range.

  As shown in Table 1, ashless coal was added to the blended coal to prepare raw coal. As ashless coal, a soluble component (ash content: 600 ppm) extracted from Australian caking coal (carbon content (daf) 84%) using 1-methylnaphthalene was used. In addition, the ashless charcoal was prepared with the following method using the apparatus of FIG. Australian caking coal (carbon content (daf) 84%) and 1-methylnaphthalene were mixed in tank 1 (Australian caking coal: 1-methyltaphthalene = 20% by mass: 80 (Mass%) slurry was prepared. The obtained slurry was heated to 370 ° C. by the preheater 3, and soluble components were extracted from the caking coal produced in Australia in the extraction tank 4. The slurry after the extraction treatment is supplied to the gravity sedimentation tank 5 at a flow rate of 15 kg / h, gravity sedimentation is performed, and the supernatant liquid and the solid phase component concentrate are separated. The supernatant liquid is filtered at a flow rate of 3 kg / h. The solid phase component concentrate was discharged from the bottom of the gravity sedimentation tank 5 to the solid phase component concentrate receiver 6 at a flow rate of 12 kg / h. The supernatant liquid was filtered by the filter unit 8 and then collected in the supernatant liquid receiver 9, and the organic solvent was removed by evaporation from the collected liquid by spray drying to obtain ashless charcoal (ash content: 600 ppm).

The coking coal, the can container of the size of width 378 mm × length 121mm × height 114 mm, were filled to a desired density (720 kg / ^{m 3} and 780kg / ^{m 3).} Four of these cans are placed in a steel retort (size: width 380 mm × length 430 mm × height 350 mm), and the retort is placed in a double-sided heating electric furnace that can heat the cans in the width direction. The coking coal was carbonized. The dry distillation was performed at 1000 ° C. for 10 hours, and then the retort was taken out of the electric furnace and allowed to cool naturally over about 16 hours.

Four can containers were taken out from the cooled retort, and a 189 mm portion of coke corresponding to half in the width direction was cut out. When performing double-sided heating, the place that hits the middle in the width direction is called a charcoal core, and the calcined coke from the heating surface to the charcoal core is called the head, body, tail from the place close to the heating surface, It is known that a difference in strength occurs due to a difference in heating rate during heating of the head, body, and tail. For this reason, the coke head, body, and tail of the 189mm portion corresponding to half of the width direction are cut into approximately cuboids (one side: approximately 20mm ± 1mm) from each part divided into approximately 60mm and sized. Got coke. The sized coke was washed with distilled water to remove fine coke powder adhering during sizing (at the time of cutting), and dried with a dryer at 150 ° C. ± 2 ° C. If the packing density of coking coal is 780 kg / m ³ so that the total size of coke after drying is 200 g, select 12, 12, and 11 in order from the head, body, and tail. When the packing density of charcoal was 720 kg / m ³ , 12 pieces, 13 pieces, and 11 pieces were selected in this order from the head, body, and tail to obtain samples for strength measurement.

Using the obtained strength measurement sample, the I-type strength was measured. As a device used for the type I strength test, a cylindrical container made of SUS material (length: 720 mm, circular bottom diameter: 132 mm) is used, and 200 g of the sample is put in this container, and rotated 20 times per minute. It was rotated at a speed for 30 minutes, and an impact due to a total of 600 rotational motions was applied. The rotation of the cylinder was performed such that a rotation axis was provided at a position of 360 mm corresponding to the middle of the cylinder length of 720 mm, and the cylinder was rotated around the rotation axis so that the bottom surface of the cylinder drawn a circle with a diameter of 720 mm. After applying an impact by the specified 600 rotations, a sample was taken out from the cylindrical container, and divided by a 9.5 mm sieve to measure the mass on the sieve. At this time, the mass caught on the sieve was also measured on the sieve and the mass was measured. The type I strength index was calculated as follows, and the calculated results are shown in Table 1.
Type I strength index I ⁶⁰⁰ _9.5 = 100 × 9.5 mm Mass on sieve (unit: g) / 200 g

In general, the rotational strength of coke is divided into one that evaluates volume fracture in which a coke lump is broken as a large lump and one that evaluates surface breakage due to surface wear, but is the type I used in the present invention. The strength index I ⁶⁰⁰ _9.5 is interpreted as an index used to evaluate surface fracture.

  From the results in Table 1, coke no. 1 to No. 5 and No. 8-No. 10 is compared, it turns out that the coke intensity | strength obtained improves by adding 1 mass part or less of ashless coal with respect to 100 mass parts of blended coal. In particular, the coke strength obtained when 0.5 parts by mass of ashless coal was added to 100 parts by mass of blended coal was the largest. In addition, coke No. 6 and no. From the result of No. 7, it was found that when the added amount of ashless coal exceeds 1 part by mass with respect to 100 parts by mass of the blended coal, the coke strength is decreased.

When the packing density of the raw coal is 780 kg / m ³ (Coke No. 1 and No. 3) and the case of 720 kg / m ³ (Coke No. 8 and No. 9), the packing density of the raw coal is It was found that the effect of improving the coke strength is greater in the case of 720 kg / m ³ .

  Coke No. 12 is coke no. Compared with 8, it is a case where the ratio of strong caking coal is low, and it turns out that the coke intensity | strength obtained is falling. However, the coke strength was improved by adding 0.5 parts by mass of ashless coal (Coke No. 13).

  In addition, coke No. 9 and coke no. 11 shows that the strength improvement effect of the ashless coal used in the present invention is larger than the strength improvement effect of the asphalt pitch.

  The present invention can be suitably applied to the production of coke and further to the production of pig iron in a blast furnace.

Explanatory drawing which illustrates the apparatus and process which manufacture ashless coal used by this invention.

Explanation of symbols

1: tank, 2: pump, 3: preheater, 4: extraction tank, 5: gravity sedimentation tank, 6: solid phase component concentrate receiver, 7: filter member, 8: filter unit, 9: supernatant receiver 10: Stirrer, 13: Stirrer

Claims (3)

100 mass of blended coal containing a coal having a carbon content (daf) of 85% to 91% and a coal having a carbon content (daf) of 60% to less than 85% The raw material coal containing 1 part by mass or less of coal containing substantially no ash is dry-distilled with respect to part, and the carbon content (daf) .) Using a soluble component obtained by extraction (excluding hydrogenation) from 60% or more and less than 95% of coal using an organic solvent . The method for producing coke according to claim 1 , wherein the organic solvent is an organic solvent containing a bicyclic aromatic compound as a main component. A method for producing pig iron, wherein coke obtained by the method for producing coke according to claim 1 or 2 is used.

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